There is a "fix" for this. Get a threaded rod coupling. . . Slide the shaft into the hole you drilled and tighted the set screws from both sides.

That is freaking genius.

If you go to a bicycle shop, they'll have a replacement cable housing that they can cut to length, used for bike brakes. The good ones have a teflon liner sleeve. That makes things much smoother.
It still doesn't hurt to spray a lube inside though, and lube the cable first, just for corrosion protection.